The analysis of components in human breath is a powerful non-invasive technique for the diagnosis and monitoring of asthma, cystic fibrosis (CF) and chronic obstructive pulmonary disease (COPD). The presence of elevated levels of nitric oxide (NO), carbon monoxide (CO), carbonyl sulfide (OCS), and ethane (C2H6) in the breath have been identified as biomarkers of these diseases, where nitric oxide and carbon monoxide are markers of airway inflammation and ethane is a marker of lipid peroxidation. In addition, carbonyl sulfide has been identified as a possible marker of cystic fibrosis. The simultaneous quantification of these components of breath would be a powerful method to identify and differentiate lung diseases and their severity. Aerodyne Research, Inc. together with the University of Massachusetts Lowell, School of Health and Environment, proposes to develop a fast response, compact, room temperature, dual quantum cascade laser based system for the quantitative analysis of multiple species in human breath by infrared absorption. In the Phase II program a dual, all thermoelectrically cooled system for detection of NO, CO2, CO and OCS in exhaled breath will be designed, constructed, and deployed in a clinical research program. In the Phase II program the spectral region for simultaneous CO and OCS detection with a single laser will be identified and laser obtained. The optical and electronic modules of the breath analyzer will be designed. The instrument will be constructed and packaged for use at a medical clinic. The instrument will be deployed in clinical research to demonstrate the instruments'utility and ease of use, and to better understand the application of biomarkers to the diagnosis and monitoring of lung disease. There will be two elements to the clinic research: the correlation of breath biomarkers with lung disease, and the characterization of NO exchange dynamics in the respiratory system and its relationship to lung disease. The proposed breath analysis instrument will meet the need in the medical community for an instrument to allow the fast, noninvasive diagnosis and monitoring of patients with lung disease. It will also be a powerful research tool for investigating exposures that initiate and exacerbate asthma and COPD.